Yeah, any idea would have to be tested out to refine it or even test the viability of it. Just the labor to convert every single canon mech would be tiring, to say nothing of converting Vehicles and BA. Constructions rules would have to be either scrapped or vastly changed to suit it.
I'd start with picking only few distinct 'Mechs to test things out. Manual construction with no codified rules. Basically i'd pick some archetypes, and maybe some mixed 'Mechs. The Rifleman, Raven, Atlas, Warhammer, Shadow Hawk would be good options for example.
I figure construction rules can be made after everything else. But even so, i'm actually inclined to just omit them completely. Just officially made units, perhaps unofficial rules for constructing unofficial units. This stems from the fact i don't actually play with custom units ever. I may play around with construction programs but that's all. That said, i would include some method of customizing your units.
Vehicles are a bit problematic because current canon and gameplay don't really agree. Vehicles are supposed to be weaker and worse than 'Mechs but cheaper. In practice, there are good vehicles for their price, and overall vehicles are not actually cheaper than 'Mechs, unless setting up 'Mech production is far more expensive.
I'm inclined to reduce vehicles to several different types (like, "heavy assault tank" could be represented by Marksman M1, Behemoth I/II or Challenger, with no functional difference) and make them mostly filler/cannon fodder. But not certain about this. I would like to make them part of the basic game though, and with roughly 12 units per side, we'd be looking at a a lance/Star/Level II of 'Mechs plus some vehicles and infantry.
Some notes on weapons and stuff:
-I'd reduce range bands to "minimum (missiles only)/optimal/maximum". Not as realistic as larger number of range bands but this would be for simplification for sake of faster and easier gameplay and reducing amount of information on record sheets that should be ideally smaller anyway.
-Missiles would be spendable weapons with limited ammo, a bit like "ordnance" in Star Wars: X-wing Miniatures Game. Promote alternate ammo for them, special tricks, etc. (Would also solve the internal volume problem of missile weapons: no technical schematic for BT ever shows where all the hundreds of missiles are stored in 'Mechs despite BT missiles being relatively small.)
-I'd probably mostly remove "cluster weapons" to reduce die rolling or otherwise modify the system, not sure. Weapon distinctions would stem from other attributes mostly.
-Weapons technology needs to be mapped from Age of War to Dark Age. Move tech around as makes sense (such as MRMs becoming basic weapons rather than 3050s tech).
-OmniMech modularity should be promoted, rather than having selection of stock configurations that work just like normal 'Mech variants.